The present invention relates to an automatic focusing position detection apparatus for use in optical instruments including cameras, and more particularly to an automatic focusing position detection apparatus of a double image overlapping type.
Conventionally, as the automatic focusing position detection apparatuses of the double image overlapping type, an automatic focusing position detection apparatus having an optical system of a trigonometrical survey type, which is capable of detecting the focusing position by moving mirrors, for instance, Visitronic Auto Focus Module made by Honeywell Co., Ltd., and an automatic focusing position detection apparatus of a TTL (Through the Taking Lens) type by use of an exit pupil divisional type taking lens, in which the taking lens or photoelectric element groups are moved forwardly or backwardly to find the focusing postition are known. However, in such automatic focusing position detection apparatuses, the focusing position can be detected, but the shift distance from the focusing position, namely the defocusing distance, cannot be measured and it is required that the mirror, the taking lens or the photoelectric element groups have to be moved to find the focusing position.